Squib switch



July 5, 1955 K, KlEL 2,712,575

SQUIB SWITCH Filed Feb. 27, 1948 J??- F [V24 24? I8 I6 JNVENTOR. F;KENNETH M. KIEL BY X 9. 6/3;

ATTORNEY United States Patent Office Patented July 5, 1955 SQUIB SWITCHAnn Arbor, Mich., assignor to the America as represented by the Secre-Kenneth M. Kiel, United States of tary of the Navy The present inventionrelates to an improved squiboperated switch which is particularlyadapted for use with projectile fuzes.

In an anti-aircraft shell equipped with a fuze, operated by a reflectedwave, hereinafter referred to an a proximity fuze, it has until theshell approaches the altitude at which it is to operate, in order toprotect any friendly aircraft, which may be near its path during thecourse of its flight at lower altitudes. This requires that the circuitfrom the battery, Which is energized when the shell is fired, to theelectronic components of the fuze shall remain open for a predeterminedtime and then be closed. Accordingly, one of the principal objects ofthe present invention is to provide a simple switch which can beactuated by an associated timing device to close a proximity fuze at adesired time, and which will be of light weight and small size to bereadily installed in the fuze.

Another similar use for the present invention is as a safety switch inany type of projectile employing an electric circuit. Said safety switchmay be closed either at the instant of launching the projectile or at adefinite time thereafter.

In the drawings:

Figure l is an axial section of the switch, greatly enlarged and showingit in open, or circuit breaking, condition.

Figure 2 is a transverse sectional view on the line 2-2 in Figure 1.

Figure 3 is an axial sectional view, on a reduced scale, of my improvedswitch in circuit closing condition.

Referring to the drawings, my entire switch is enclosed in a cylindricalcase 10. The fixed portion of the switch is supported by a cylindricalblock 12 of insulating material held in position in the crimped rim 14and by crimping over the adjacent end of said case, as shown at 16.Spaced conductors 18 are molded into the block 12 and have inner endportions bent radially inwardly to form opposed spaced spring contacts20 projecting over a conical depression 22 in the inner face of theblock, while the outer end portions 24 project beyond the outer end wallof the block 12 to form terminals for external circuit connections.

The movable portion of the switch includes a conducting ring 26 mountedon and at the base of an axially located stud 28 formed on a plunger 30axially movable in the case 10. Said stud passes between the springcontacts 20 and is guided by an axial cylindrical bore 32 whichcommunicates with the conical depression 22 in the fixed block 12. Theouter end of the conducting ring 26 is provided with a substantiallyfrusto-conical flange 34 which can be moved past the spring contacts 20in one direction but which is held by them to prevent motion in thereverse direction. The plunger is normally positioned to hold the ring26 away from the contacts 20 by the inter-engagement of a flange 36 onthe plunger been found desirable to keep the fuze inert the batterycircuit of case 10 by an annular inwardly with an annular inwardlycrimped rim 38 formed in the case in spaced relation to the rim 14.

An explosive charge 40 is confined in a cup 41 defined by a liner 42 anda block 44, both of insulating material. The block 44 closes the lowerend of the case 10 (as seen in Figure 1) and is held in place bycrimping over the end margin of said case, as shown at 48. Said block isreduced in diameter near its upper end to define an annular recess toreceive the lower end of the liner. A filament 50 for exploding thecharge 40 is embedded in said charge and is supported by leads 52 whichare embedded in the block 44. Said leads, like the leads 24, areextended beyond the case to define terminals.

In use, the electrical circuit to be controlled is connected to theswitch leads 24, and the control circuit is connected to the filamentleads 52. The control circuit is energized at the time when operation ofthe switch is desired. If such operation is to start as the projectileis launched, the control circuit may be connected to the firing circuit;while, if operation is to start at a later time, the control circuitwill include a voltage source and a suitable time switch to complete thecircuit. In either case, energizing of the control circuit causes thefilament 50 to heat and explode the charge 40. The charge issufiiciently powerful to force the flange 36 of the plunger 30 past theannular crimp 38 and toward the bolck 12, driving the conical flange 34of the ring 26 on the stud 28 past the contacts 20 to permit the ring tocomplete the controlled circuit between them. The charge 40, however, isnot powerful enough to break the case 10 and damage any surroundingequipment.

The invention is defined solely in and by the following claims.

I claim:

1. An electrical switch for a projectile fuze, said switch having acylindrical case, a pair of opposed resilient contact members supportedin one end thereof and terminating at an angle to the axis of the case,an axially shiftable plunger in the case, a central cylindrical stud onsaid plunger passing between the resilient contact members, aring-shaped contact member on said stud and inteiposable between saidresilient contact members said ring-shaped contact member having afrusto-conical flange formed on one edge thereof, means on said case fornormally resisting any tendency of the plunger to move axially to bringthe ring-shaped contact member into engagement with the resilientcontact members, and explosive means carried in said case for propellingsaid plunger axially in the case to overcome the resistance of saidfirst mentioned means to cause the terminations of the resilient contactmembers to slide over and snap behind the said flange and to lock thering-shaped contact member in engagement with the resilient contactmembers.

2. An electrical switch for the fuze of a projectile, said switch havinga cylindrical case, a pair of opposed resilient contact memberssupported in one end thereof, an axially shiftable plunger in the case,a central cylindrical stud on said plunger passing between the fixedcontact members, a ring-shaped contact member on said stud andinterposable between said fixed contact members, said case having a beadinternally thereof for normally resisting any tendency of the plunger tomove axially to bring the ring-shaped contact member into engagementwith the fixed contact members, electrically fired explosive means forpropelling said plunger axially in the case to overcome the resistanceof said bead and bring the ring-shaped contact member into engagementwith the fixed contact members, and a flange on said ring-shaped contactmember engaged by the resilient contact members for preventing motion ofthe plunger in the reverse direction.

3. A fuze switch for use with an explosive projectile,

comprising a sheet-metal case of generally cylindrical configurationhaving two spaced beads formed inwardly in the central portion thereof,a block of insulating material in one end of the casing and held inplace by one of said beads, said block having a recess formed in theinner transverse surface thereof, said recess comprising a large conicalwalled portion which merges interiorly into a relatively narrowcylindrical bore, a block of explosive material situated in the otherend of the casing and having an ignition filament embedded therein, aplunger of insulating material having a generally disk-like shapesituated between said blocks and having an annular shoulder whichnormally resides adjacent the other of said beads on the side thereofaway from the first-mentioned bead, said plunger having a stud extendingaxially therefrom and of such size and shape as to slide freely in thebore portion of said recess, two conductors embedded in said block ofinsulating material and having resilient free ends which extend intosaid recess, the free ends extending radially into said recess fromopposite directions and terminating at an angle to the axis of thecontainer and directed toward said bore, and a ring of conductivematerial fixed around said stud at the portion thereof adjacent theplunger, the edge of said ring which is away from said plunger having afrusto-conical flange having its surface formed to mate with theterminations of the free ends of the conductors, whereupon ignition ofsaid explosive by said filament throws said plunger toward saidconductors to force said ring between them.

4. In a switch of the type having a casing, a plunger slidable in saidcasing, contact members fixed relative to said casing, and an explosivemember for propelling said plunger into position against said contactmembers, a bead formed in said casing adjacent said explosive memher, ashoulder on said plunger located adjacent said bead whereby said plungeris normally maintained away from said contact members, said contactmembers terminating in opposed portions directed at an angle to thedirection of motion of the plunger and in a direction away from saidplunger, said plunger being provided with a ring of conducting materialhaving a frusto-conical flange formed on the edge thereof which isdirected toward the contact members, the large portion of thefrusto-conical flange being directed away from the contact members sothat movement of the flange past the contact members due to movement ofthe plunger permits the contact members to snap behind the flange intocontact with the ring and to prevent the plunger from returning to itsinitial position.

References Cited in the file of this patent UNETED STATES PATENTS535,069 McElroy et al Mar. 5, 1895 769,824 Hopkinson Sept. 13, 19041,116,458 Matos Nov. 10, 1914 1,159,602 Scheuer Nov. 9, 1915 1,630,359Scott May 31, 1927 2,235,917 Campbell Mar. 25, 1941 2,330,690 DannerbergSept. 28, 1943 2,559,024 McFarlin July 3, 1951

